I have a speech language pathologist treating patients for speech disorders related to autism. She is coding the dx as 315.3x for "Developmental speech or language disorder". It is difficult to get this paid if the patient does not have specific coverage for slp. Some states have specific guidelines for autism mandating coverage for SLP. My question is - Is it appropriate to code code 315.3x as primary and add a secondary diagnosis for austism (299.0x) as the only reason she is treating the patient is a result of the austism?